The invention relates to a stacking device for letters and similar flat, flexible articles to be transported, the device including a plurality of stacking compartments which receive the articles by way of switches separately associated with the individual compartments, and with the articles being stacked next to one another and wherein an additional conveying device is disposed in each stacking compartment between the transporting roller and the stacking roller so as to urge the lower edge of each incoming article in the direction of the stack approximately perpendicularly to the transporting direction.
In automatic mail distribution systems, the articles are transported individually over a conveying path for the purpose of automatically reading their destination and later sorting them and, by way of a compartmented path equipped with switches, they are assigned according to their postal code regions to a plurality of stacking compartments where they are stacked.
In order to obtain the highest possible throughput, the articles move on the conveyor belt with the greatest possible speed and with the smallest possible distances between them. Under these circumstances, the problem of congestion occurs in connection with articles assigned to the same stacking compartment. This is caused by the leading edge of the subsequent article running onto the trailing edge of the preceding article.
DE-OS 3,317,865 discloses a system in which vertically stacked articles resting on their lower longitudinal edge enter the system in that their lower front edge enters tangentially into a rotating spindle wheel and, in the course of the article entering into the stacking compartment, the side of the spindle wheel transports the subsequent portions of the article, particularly its rear region, in the direction of the already stacked articles so that the subsequent article will reliably enter the stacking compartment next to the preceding article.
However, a spindle wheel drive for each stacking compartment is very complicated and expensive, particularly for fine distribution systems which employ a large number of small capacity stacking compartments and operate with a smaller throughput.